Space Invaders
Platform: Sega SG-1000
Region: Japan
Media: Cartridge
Controller: SG-1000 Joystick
Genre: Shooter 
Gametype: Licensed
Release Year: 1985
Developer: SEGA
Publisher: SEGA
Players: 1 or 2 Alternating
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Attention all Earthlings! Relentless alien hordes have been identified near you. Prevent the dangerous Space Invaders from landing on your territory. Use your cannon to defend against waves of descending alien invaders. Don't let them hit the ground or it's all over for you and the Earth! Destroy them and score points!

http://www.gamefaqs.com/console/sg1000/home/916313.html